Method for producing fine powder and the fine powder produced by the same

Abstract

Disclosed is a manufacturing method for a fine powder exhibiting improved solubility, little impurity contamination, and a high recovery rate. Material to be ground and a grinding medium are suspended and stirred in a liquefied inert gas dispersion medium such as dried ice, and the material to be ground is made into a sub-micron or nano-sized fine powder. A uniform fine powder can be obtained when the material to be ground is a mixture having two or more components. Impurity contamination can be reduced by using granular dry ice as the grinding medium.

The invention claimed is: 
     
       1. A method for producing fine powder, comprising the steps of:
 suspending two or more kinds of original materials in liquefied inert gas that is used as disperse medium to form a slurry, and putting grinding medium in said slurry, and then stirring said slurry to pulverize said original materials into submicron sized and/or nano-sized particles, wherein said grinding medium consists entirely of dry ice beads so that said original materials are pulverized by said dry ice beads in said liquefied inert gas; 
 sublimating said dry ice beads from said slurry; and 
 vaporizing said liquefied inert gas from said slurry to recover a mixture of said two or more kinds of original materials having improved solubility and/or degree of homogeneous mixing. 
 
     
     
       2. The method as recited in  claim 1 , characterized in that said two or more kinds of original materials are concurrently pulverized in said liquefied inert gas. 
     
     
       3. The method as recited in  claim 1 , characterized in that said original material comprises bulk of medicines and additives for medicines. 
     
     
       4. The method as recited in  claim 3 , characterized in that said additives are water-soluble additives or dispersion accelerating agents for medicines, selected from the group consisting of Hypromellose-Acetate-Succinate (HPMCAS), polyvinylpyrrolidone (PVP), Methacrylic Acid Polymer (Eudragit L100), carboxymethylcellulose (CMC), microcrystalline cellulose (MMC), low substituted hydroxy-propylcellulose (L-HPC), hydroxypropyl-cellulose (HPMC), and lactose. 
     
     
       5. The method as recited in  claim 1 , characterized in that said liquefied inert gas is liquid nitrogen, liquid helium, liquid neon, liquid argon, liquid krypton, or liquid xenon. 
     
     
       6. The method as recited in  claim 1 , characterized in that said grinding medium is zirconia, agate, quarts, titania, tungsten carbide, silicon nitride, alumina, stainless steel, soda glass, low soda glass, soda less glass, high density glass or dry ice (carbon dioxide, nitrous oxide), and the diameter of said grinding medium is within the range from 0.03 to 25 mm. 
     
     
       7. A method for producing fine powder, comprising the steps of:
 suspending original material in liquefied inert gas that is used as disperse medium to form a slurry, and putting granular dry ice in said slurry, and stirring said slurry by a pulverizer to pulverize said original material by means of said granular dry ice functioning as grinding medium in said slurry. 
 
     
     
       8. The method as recited in  claim 7 , characterized in that the particle diameter of said granular dry ice reduces as said original material is pulverized. 
     
     
       9. The method as recited in  claim 7 , characterized by the steps of: pulverizing said original material in said slurry; and then vaporizing said liquefied inert gas from said slurry and sublimating said granular dry ice to obtain pulverized dry particles of said original material. 
     
     
       10. The method as recited in  claim 8 , characterized in that said original material is pulverized to the particles having desired particle sizes without exchanging said granular dry ice. 
     
     
       11. The method as recited in  claim 7 , characterized in that said disperse medium does not include dispersion agents. 
     
     
       12. The method as recited in  claim 7 , characterized in that said granular dry ice comprises solid particles of carbon dioxide and the particle diameters of said solid particles are in the range from 0.01 to 25.00 mm. 
     
     
       13. The method as recited in  claim 7 , characterized in that said granular dry ice comprises solid particles of carbon dioxide and the particle diameters of said solid particles are in the range from 0.30 to 1.00 mm. 
     
     
       14. The method as recited in  claim 7 , characterized in that said granular dry ice comprises solid particles of carbon dioxide and the particle diameters of said solid particles are in the range from 0.03 to 0.30 mm. 
     
     
       15. The method as recited in  claim 7 , characterized in that said liquefied inert gas is at least one liquid gas selected from the group of liquid nitrogen, liquid helium, liquid neon, liquid argon, liquid krypton, and liquid xenon. 
     
     
       16. The method as recited in  claim 7 , characterized in that said original material is bulk of medicine. 
     
     
       17. The fine powder of said original material produced by the method as recited in  claim 7 . 
     
     
       18. A method for producing fine powder, characterized by the steps of: suspending original material in liquefied inert gas that is used as disperse medium to form a slurry, and putting beads for pulverization or dispersion in said slurry and stirring said slurry and said beads by a pulverizer to pulverize said original material by means of said beads in said slurry; wherein said beads consist essentially of granular dry ice. 
     
     
       19. The method as recited in  claim 18 , characterized in that said liquefied inert gas is liquid nitrogen and said pulverizer is a bead mill. 
     
     
       20. The method as recited in  claim 18 , characterized in that said granular dry ice comprises solid particles of carbon dioxide and the particle diameters of said solid particles are in the range from 0.30 to 1.00 mm. 
     
     
       21. The method as recited in  claim 18 , characterized in that the particle diameter of said granular dry ice reduces as said original material is pulverized. 
     
     
       22. The method as recited in  claim 21 , said original material is pulverized to the particles having desired particle sizes without exchanging said granular dry ice. 
     
     
       23. The method as recited in  claim 18 , characterized in that said disperse medium does not include dispersion agents. 
     
     
       24. The fine powder of said original material produced by the method as recited in  claim 18 .